TWI538815B - Method and apparatus for joining together multiple functional layers of a flexible display - Google Patents

Description

Method and apparatus for joining multiple functional layers of a flexible display together

Some example embodiments of the present invention generally relate to joining a plurality of layers of a display of a device with an optical clear adhesive, and more particularly, for providing greater flexibility for use at a particular location on the display. An optically clear adhesive bonds the layers of a flexible display.

In recent years, considerable progress has been made in the development of thin flexible displays. For example, a display device assembly is known that includes a flexible display device that is crimpable about an axis. Flexible electronic devices based on these technologies, including one of full-color, high-resolution flexible organic light-emitting diode OLED displays having a thickness of less than one millimeter, are being introduced to the market. The goal of these efforts is to provide superior control, contrast and flexibility to the display.

While conventional displays are made from a plurality of layers of rigid materials such as glass and hard polymers, flexible displays employ multiple layers of flexible materials such as films. Flexibility may add durability to the display and may increase functionality via additional user input mechanisms. However, the flexibility of such flexible displays is used to produce displays The material and the movement between the layers of the display during flexing are at least partially confined.

A method and apparatus are provided to enable improved flexibility of a flexible display by using a special assembly to enhance the flexibility of the display, particularly in areas where maximum deflection may occur.

An exemplary embodiment may provide a method comprising laminating a layer of optically clear adhesive on a first substrate and laminating a second substrate opposite the first substrate on an optically clear adhesive. The optically clear adhesive may comprise a first region of a first modulus of elasticity and a second region of a second modulus of elasticity, wherein the second modulus of elasticity is different from the first modulus of elasticity. Optically clear adhesives may include a liquid optical clearing agent, or optically clear adhesives may be a film. The method may include crosslinking the optically clear adhesive of the first region to a first extent, and crosslinking the optically clear adhesive of the second region to a second extent different than the first extent. Crosslinking of the optically clear adhesive may be effected by exposure to ultraviolet radiation, and the second region of the optically clear adhesive may be blocked from exposure to at least a portion of the ultraviolet radiation. Crosslinking of the optically clear adhesive may optionally be carried out by application of thermal energy or a chemical crosslinking agent. The layering of one of the optically clear adhesives may include printing a pattern of a first optically clear adhesive to form the first region of the optically clear adhesive. The layer of optically clear adhesive may additionally include printing a second pattern of a second optically clear adhesive to form the second region of the optically clear adhesive. The second modulus of elasticity may be lower than the first modulus of elasticity, and the second region of the optically clear adhesive may define a region of high flexibility.

Embodiments of the invention may provide a device that includes a display stack. The display stack may include a first substrate, a layer of optically clear adhesive deposited on the first substrate, and a second substrate. The layer of optically clear adhesive may define a first region having a first modulus of elasticity and a second region having a second modulus of elasticity, wherein the first modulus of elasticity is different from the second modulus of elasticity. The second modulus of elasticity may be lower than the first modulus of elasticity, and the second region of the optically clear adhesive may define a larger area than one of the display stacks defined by the first region of the optically clear adhesive An area of a flexible display stack. Optical clear adhesives may include a liquid optical clear adhesive. The liquid optical clear adhesive may crosslink to a first extent in the first region and crosslink to a second extent different from the first extent in the second region. The first region of the optically clear adhesive can be cured in response to exposure to ultraviolet radiation.

Embodiments of the present invention may provide a display stack comprising a first substrate, a layer of optically clear adhesive disposed on the first substrate, and a second substrate. The layer of optically clear adhesive may define a first patterned region having a first index of refraction. The layer of optically clear adhesive may define a second patterned region comprising a second index of refraction. The first index of refraction may be different from the second index of refraction; however, the first index of refraction may also be the same as the second index of refraction. The first patterned region and the second patterned region may comprise the same optically clear adhesive, and wherein the first patterned region may be aged to a first degree and wherein the second patterned region may be aged to a first degree Different from a second degree. The first patterned area may be exposed to ultraviolet radiation to cure it. First patterned area and second The patterned regions may each comprise a different optically clear adhesive. The first patterned area may be printed onto the first substrate.

10‧‧‧Mobile terminal

14‧‧‧transmitter

19‧‧‧ converter

22‧‧‧ electric bell

26‧‧‧Microphone

30‧‧‧ keyboard

12‧‧‧Antenna

16‧‧‧ Receiver

20‧‧‧ processor

24‧‧‧ Horn

28‧‧‧Display

31‧‧‧ Sensor

38‧‧‧UIM

40‧‧‧Electrical memory

42‧‧‧ Non-electrical memory

100‧‧‧Layered stacked display

110, 210‧‧‧ first substrate layer

120, 220‧‧‧Second substrate layer

130‧‧‧Optical Clear Adhesive (OCA)

134‧‧‧High modulus of elasticity area OCA

136‧‧‧Low elastic modulus area OCA

140, 270‧‧ ‧ folding line

150‧‧‧Liquid OCA with a modulus of elasticity X

160‧‧‧Substrate

170‧‧‧Liquid OCA with a modulus of elasticity Y

180‧‧‧UV radiation and / or heat

190‧‧‧Second substrate

200‧‧‧ Liquid Optical Clear Adhesive (LOCA) material

225‧‧‧Hot or ultraviolet radiation

230‧‧‧ shadow mask

240‧‧‧ Covered part

250‧‧‧Uncovered part

260, 300‧‧‧ display stacking

280‧‧‧Low elastic modulus area

290‧‧‧High modulus of elasticity area

310‧‧‧A region with a lower refractive index

320‧‧‧Cylindrical region with higher refractive index

330‧‧‧Top substrate

340‧‧‧Display substrate/base substrate

350‧‧‧Face glass substrate

360‧‧‧Bending glass cover window

410, 420, 430‧‧ steps

Although the embodiments of the present invention have been described in a broad language, the embodiments of the present invention are not necessarily drawn to scale, and wherein: FIG. 1 is a mobile terminal that may benefit from an exemplary embodiment of the present invention. A schematic block diagram; FIGS. 2A, 2B, and 2C illustrate a display stack having a selectively patterned optically clear adhesive in accordance with an exemplary embodiment of the present invention; FIG. 3 illustrates a pattern of liquid optical clear adhesive in accordance with the present invention. Example embodiment of a chemical buildup process; FIG. 4 illustrates an exemplary embodiment of a patterned optically clear adhesive produced by selective curing of a uniform layer in accordance with the present invention; FIG. 5 illustrates an alternative in accordance with the present invention. Example embodiment of a patterned optically clear adhesive; Figure 6 illustrates an exemplary embodiment of a selectively patterned optically clear adhesive having a vertically aligned, higher index of refraction cylindrical region in accordance with the present invention; The present invention is illustrative of a light-guide optically clear adhesive for directing light from a display to a cover glass; Figure 8 is a flow diagram of an exemplary embodiment of selectively patterning an optically clear adhesive in accordance with the present invention. Figure.

Certain embodiments of the present invention will now be described hereinafter with reference to the accompanying drawings More fully described, some but not all embodiments of the invention are shown in the drawings. Indeed, the various embodiments of the invention may be embodied in a variety of different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that the disclosure will satisfy the appropriate legal requirements. . The same reference numerals are used throughout the specification to identify the same elements. As used herein, the words "material", "content", "information" and the like may be used interchangeably to refer to a material that can be transmitted, received, and/or stored in accordance with certain embodiments of the present invention. Therefore, the use of any such terms should not be used to limit the spirit and scope of the embodiments of the invention.

Moreover, as used herein, the term "circuitry" is used to mean (a) a hardware-only circuit implementation (eg, in analog circuitry and/or in a digital circuitry); (b) a circuit and a combination of computer program products comprising software and/or firmware instructions stored on one or more computer readable memories, the instructions operating together to cause a device to perform one of the methods described herein Or a plurality of functions; and (c) a circuit such as a microprocessor or a portion of a microprocessor that requires a software or firmware for operation, even if the software or the firmware is not physically present. The definition of "circuitry" applies to all uses of this term in this document, including in any request. As another example, as used herein, the term "circuitry" also includes an embodiment that includes one or more processors and/or portions thereof and associated software and/or firmware. As another example, the term "circuitry" as used herein also includes, for example, a baseband integrated circuit or application processor integrated circuit for a mobile phone, or a server, a cellular In network devices, other network devices, and/or other computing devices A similar integrated circuit.

Certain embodiments of the present invention may be directed to providing a mechanism for joining together a plurality of substrate layers of a flexible display with an optically clear adhesive that allows for improved substrate stacking. It is also flexible and may also optically direct the image to a location on the surface of a display that is misaligned with the display layer in a stack of substrate layers. Embodiments of the present invention may provide an improved user interface that can include increased flexibility and enhanced optical properties.

1 illustrates a block diagram of a mobile terminal 10 that may benefit from embodiments of the present invention. However, it should be understood that the mobile terminal 10 as illustrated and hereinafter described is merely illustrative of one form of apparatus that may benefit from embodiments of the present invention and, therefore, should not be taken as limiting the embodiments of the present invention. range. So, for example, portable digital assistants (PDAs), mobile phones, pagers, mobile TVs, gaming devices, laptops, cameras, tablets, touch surfaces, wearable devices, video recorders, audio/video playback , radio, e-books, positioning devices (such as Global Positioning System (GPS) devices), or any combination of the above, and other forms of voice and various forms of mobile terminal systems, may easily use this Embodiments of the invention, but other devices including stationary (non-operating) electronic devices may also employ certain example embodiments.

Mobile terminal 10 may include an antenna 12 (or multiple antennas) in operative communication with a transmitter 14 and a receiver 16. Mobile terminal 10 may additionally include a device such as a processor 20 or other processing device (e.g., processor 70 of FIG. 2) that controls the provision of signals to transmitter 14 and reception, respectively. The device 16 and the action of receiving a signal from the transmitter 14 or the receiver 16. The signal may include messaging information according to the empty intermediaries standard of the applicable cellular system, as well as user utterances, received data, and/or user generated data. In this regard, the mobile terminal 10 can operate using one or more empty interfacing standards, communication protocols, modulation patterns, and access patterns. By way of illustration, the mobile terminal 10 can operate in accordance with any of a variety of first, second, third, and/or fourth generation communication protocols or the like. For example, mobile terminal 10 may be capable of operating in accordance with the following communication protocols: second generation (2G) wireless communication protocol IS-136 (time division multiple access (TDMA)), GSM (global mobile communication system), and IS-95 ( Fragmented Multiple Access (CDMA), or third generation (3G) wireless communication protocols such as Universal Mobile Telecommunications System (UMTS), CDMA2000, Wideband CDMA (WCDMA), and Time Division Synchronous CDMA (TD-SCDMA), such as Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) 3.9G wireless communication protocol, fourth generation (4G) wireless communication protocol (such as Long Term Evolution (LTE) or Long Term Evolution System (LTE-A)) or Similar to others. As an alternative (or in addition), the mobile terminal 10 may be capable of operating in accordance with a non-cellular communication mechanism. For example, mobile terminal 10 may be capable of communicating over a wireless local area network (WLAN) or other communication network.

In some embodiments, processor 20 may include circuitry that is intended to perform the audio and logic functions of mobile terminal 10. For example, processor 20 may be comprised of a digital signal processor device, a microprocessor device, and various analog to digital converters, digital to analog converters, and other support circuits. The control and signal processing functions of the mobile terminal 10 are based on this The individual capabilities of these components are assigned to them. Processor 20 may therefore also include the functionality to gyrocode and interleave messages and data prior to modulation and transmission. Processor 20 may additionally include an internal voice coder and include an internal data modem. Additionally, processor 20 may include functionality to operate one or more software programs that may be stored in memory. For example, processor 20 may be capable of operating a linked program such as a conventional web browser. The connectivity program may allow the mobile terminal 10 to send and receive content such as location-based content and/or other web content, for example, according to a Wireless Application Agreement (WAP), Hyper-Transport Protocol (HTTP), and/or the like. Web content.

The mobile terminal 10 may also include a user interface that includes all of an output device such as a conventional earphone or speaker 24 coupled to the processor 20, an electric bell 22, a microphone 26, a display 28, and a use. Input interface. The user input interface that allows the mobile terminal 10 to receive data may include any of a variety of devices that allow the mobile terminal 10 to receive data, such as a keyboard 30, a touch display (the display 28 provides one of such touch displays) Example) or other input device. In an embodiment that includes keyboard 30, keyboard 30 may include conventional numbers (0-9) and associated keys (#, *), and other hard and soft keys used to operate mobile terminal 10. Alternatively or additionally, keyboard 30 may include a conventional QWERTY keyboard arrangement. Keyboard 30 may also include a variety of soft keys with associated functionality. Additionally, or alternatively, the mobile terminal 10 may include an interface device such as a joystick or other user input interface. Certain embodiments employing a touch display may completely omit the keyboard 30 and any or all of the speakers 24, the bell 22 and microphone 26. Embodiments of the mobile terminal may additionally include, for example, a converter 19 as part of the user interface. Converter 19 may be used to provide a tactile feedback to a user. Haptic feedback may be provided in response to input received by a user or by a mobile terminal to provide tactile notification to a user.

A display of the mobile device, such as display 28 of mobile terminal 10, may use a multi-layer display to enable the functionality of the display to be implemented. For example, a touch screen display may include a transparent surface layer, one or more transparent conductive layers (eg, for enabling touch input), a rigid glass layer and a light emitting diode (LED), organic A light emitting diode (OLED) or liquid crystal display (LCD) layer. Multiple displays (eg, polymer dispersed liquid crystal (PDLC) or other reflective LCD displays, electrophoretic (EP), electroluminescent (EL), electrowetting (EW) electrochromic (EC) or such as based on suppressed internal reflection or Other optical modulation effects of the interference of the Fabry Perot cavity) will use a variety of substrate layers including or omitting the layer described above, as well as a number of other substrates that may provide additional durability, functionality, and the like. The layers are assembled. However, in each case, the layers need to be joined to each other, such as via an adhesive, to provide a clear and usable display. Optical Clear Adhesives (OCAs) are commonly used to join together multiple functional layers in an electronic device that includes an electronic display. OCA provides means for joining together components such as a display window, touch screen, polarizer, and display (such as an LCD display) to form a final display stack that may subsequently be integrated into the device. OCA must provide sufficient adhesion and transparency to ensure that the display stack is strong enough to withstand long-term use and environmental conditions, especially when the display stacks are often A touch screen used to interact with the device.

Conventional displays are substantially rigid and include a glass or other substrate, and recent developments have enabled the production of flexible displays that may have additional benefits. Flexible displays may contribute to an additional degree of interactivity and additional form factors to the electronic device. For example, an "action device" may use a flexible organic light emitting diode (OLED) display that can be bent and twisted to select, scale, and the like. Such flexible devices may impose more stringent requirements on the OCA materials used to bond the display stack substrates together, as the layers in the OCA and display stacks will be larger compared to a conventional rigid stack. Stress and strain. In an exemplary embodiment of a folding display, the display stack and OCA will be subjected to extreme stresses and strains along the fold line because the radius of curvature may be quite small.

In an exemplary embodiment of a flexible electronic device, the display stack may contain several layers including a display, a touch screen, and a display window, all of which may need to be joined together with sufficient adhesion and transparency. To allow touch interaction with the device as well as distortion and bending interaction. This bonding can be accomplished by using an OCA material in the form of a film that is applied to adjacent layers by applying heat, pressure, UV radiation, chemical curing, or some combination of these means during lamination. In order to allow for extreme deformation (eg, folding), the OCA material must be capable of allowing a substantial amount of slip between the various component layers, as well as providing some strain relief between, for example, the display and the touch screen or between the display and the display window. . At the same time, OCA materials must also provide adhesion between the functional layers.

The text provided in this paper is used to implement one of the OCA layers. The OCA layer has selectively patterned regions having different elastic modulus and refractive index to allow positioning of the central axis of the laminated film and to produce a visual display effect. An exemplary embodiment of an OCA layer comprising regions of different elastic moduli may control the stress on a flexible display fold line. The use of a selective patterning and maturation step allows for the creation of an adhesive tie layer which can be: rigid, properly adhered, provides rigidity, robustness, and prevents sagging of the substrate, and has a low A plurality of elastic modulus or regions that remain liquid and allow high shear strain and significant bending without causing significant stress and without separating the substrate layers from each other.

Figure 2 illustrates an OCA structure that may allow for selective patterning with minimal strain transfer along a fold line. A front view of one of the layered stacked display 100 is shown in FIG. 2A, and FIG. 2B illustrates a contour view of the same layered stacked display 100. This layered stack is simplified to include only two substrate layers; however, embodiments may include multiple layers, each joined via a patterned OCA structure. The first substrate layer body 110 is separated from the second substrate layer body 120 by a layer of an OCA 130. The OCA 130 may include a region OCA 136 of low modulus of elasticity and an area OCA 134 of one of the higher modulus of elasticity that is stiffer than the region of low modulus of elasticity. These regions can be selectively patterned such that the low modulus region OCA 136 is disposed adjacent to one of the fold lines 140 around which the layered stacked display 100 can be bent or folded. 2C illustrates the stacked display 100 folded about the fold line 140 such that the low modulus of elasticity OCA is flexed while the higher modulus of elasticity OCA 134 remains undeflected. When the substrate layers move relative to each other, the OCA disposed between the substrate layers undergoes high shear adjacent to the bend/fold, while the OCA 134 disposed between the substrate layers does not experience the same while remaining undeflected. Kind of shear.

The methods described herein produce several methods of patterning OCA materials. While the methods described herein may be related to joining two substrates together, as will be apparent to those of ordinary skill in the art, the joining methods may be repeated or combined with other joining methods to join the additional layers together. To form a complete display stack. Therefore, the examples provided herein are understood to be repeated for multiple layers when necessary.

A first exemplary embodiment may include selective printing using a liquid optical clear adhesive (LOCA) to create a patterned region of OCA on one or both substrates to which the substrate is to be joined. LOCA may be cured or partially matured using thermal and/or ultraviolet (UV) radiation exposure and/or chemical crosslinking. As shown in Figure 3, two different LOCA materials having different elastic moduli when matured can be successively printed to produce an adhesive layer of patterned regions having different tenacities. A substrate 160 may be selectively patterned by LOCA 150 having an elastic modulus X upon aging. The uncoated areas of the substrate may, in some embodiments, be left blank to create an air gap. Alternatively, the uncoated area may be patterned with another LOCA 170 having a modulus of elasticity Y. The second substrate 190 may be laminated over the LOCA 150, 170. The lamination may be performed under vacuum to remove air bubbles. The stack may then be uniformly exposed to UV 180 (and/or heat) to mature the LOCA and join the two substrates together. The result is an OCA layer with different elastic modulus regions.

Depending on the patterning method used to build the two forms of LOCA, some variations of this basic approach can be used. For example, in the case of not destroying the first wetting layer of LOCA, it may be difficult to apply a second to the template. The wetting layer is between the regions of the first wetting layer because the template may require intimate contact with the imprinting layer to achieve proper material transfer through the template to the substrate. A thick metal template may be used in which the pocket is etched on the bottom side to allow the template to contact the substrate without damaging the first wetting layer of the LOCA. If the second overprinted LOCA has a moderately low viscosity and is sufficiently wetted on the substrate, the second overprint of LOCA will be dispersed on the substrate to completely fill the gap left by the first LOCA. The same problem may occur with screen printing because the wiper blade of a screen printing device may force the screen to contact the first wet layer of the existing LOCA. This problem can be avoided by using an ink jet printer or a valve jet printer or sprinkler to build a second wetting layer between the first wetting layers. Alternatively, the first OCA layer may be a dry film adhesive that may be removed before or after lamination to produce a desired pattern, and the second LOCA layer may be overprinted or coated to the first In the gap inside the layer.

Another method for overprinting the second layer may be to laminate the second substrate after patterning the first LOCA material, exposing the substrate to UV radiation or heat to cure, and then backfilling the air gap with the second LOCA material. . This method may be practiced under vacuum using methods similar to those used to fill LCD displays with liquid crystal solutions. The cavity can be placed in the LOCA material and a vacuum can be applied; when the vacuum is removed, the LOCA fills the gap. Screen or stencil printing may be used to pattern the first LOCA material, and this method may provide distinct boundaries between two different cured OCA materials, as it does not occur when the LOCA material is wet adjacent to the overlay. Diffusion or mixing that may occur. The second LOCA material can be cured if desired.

According to certain exemplary embodiments, only a single patterned LOCA layer may be deposited between the two substrates to be joined, and an air gap may be left between the coated topography to allow the stack to undergo extremes such as folding. There is minimal stress transfer during strain. In other embodiments, a refractive index matching liquid may be used to fill the air gap after the lamination step, which minimizes stress transfer, but may also avoid large changes in refractive index between an aged OCA and an air gap. Any unwanted optical (eg, scattering or diffractive) effects that may occur.

Other embodiments may include a pre-patterned substrate to include an elevated shore/wall such that the first LOCA and the second LOCA material can be printed on separate blocks to prevent or reduce their mixing prior to ripening. For example, the plastic may include an imprinted microrepetitive or nanoimprint, and the flexible glass may include overprinting and curing of narrow boundary blocks, which may be performed as described above.

Another exemplary embodiment of the invention may include selective maturation of a uniform LOCA film to produce patterned regions of different elastic modulus. In this embodiment, a LOCA may first be dispersed by a thin film coating technique such as slot-die coating, strip coating, rod coating, knife coating or the like to form A wet film of uniform thickness. The substrates to be joined may then be stacked together under vacuum to remove any unwanted bubbles. For UV radiation that can be cured by UV radiation, UV radiation exposure can be performed via a mask having a desired pattern such that certain areas of the LOCA receive a greater amount of UV exposure and become crosslinked to less than others The area of exposure is higher. A region with a higher degree of cross-linking may have a higher modulus of elasticity than a region with a lower crosslink density.

Optionally, a thermally cured positive photoresist LOCA can be used in conjunction with a photoinhibitor. In this embodiment, the OCA region exposed to UV radiation and heat curing may have been photosoftened relative to the unexposed regions. One of the advantages of this embodiment may include combining the crosslinker and the base monomer with a photoinhibitor that renders them resistant to further ripening. The use of a shadow mask allows for a quick selective exposure of the entire sample, but with minimal control over exposure in the area of the mask. Optionally, a source of UV points such as a UV LED or laser may be used to selectively write into a small area of the LOCA. While this may be more accurate and provides greater control over UV exposure in all areas of the sample, this embodiment may require more time to implement.

Figure 4 illustrates an exemplary embodiment of a selective curing of a uniform layer. In the illustrated embodiment, a layer of uniform LOCA material 200 may be interspersed onto a first substrate layer 210 by a conventional film coating process. A second substrate layer 220 may be laminated over the LOCA material 200 under vacuum. A shadow mask 230 may be applied over the layered stack (first substrate 210, LOCA 200, and second substrate 220), and the stack of masks may be exposed to heat or UV radiation 225. Exposure to heat or UV radiation produces regions having different crosslink densities depending on whether they are part of the masked 240 or unmasked portion of the LOCA 200. The difference in cross-linking results in different elastic modulus regions.

Additionally or in lieu of UV curing, selective thermal curing can be used in a similar manner to create regions of different elastic modulus. For example, a resin material such as polydimethyl siloxane (PDMS) can be crosslinked to varying degrees depending on the curing temperature. After stacking the two substrates, the heat can use an infrared (IR) heater with a shadow mask, an IR point curing system (such as a laser) or a direct use of a picture The heat transfer plate is applied. The latter method is particularly useful when the substrate is opaque to UV radiation.

Some example embodiments of LOCA may include moisture vatable resin LOCA, wherein the substrate can be selectively patterned by overprinting water prior to coating the LOCA. Once laminated, UV curing will only ripen the LOCA block that is in contact with water. The water patterning and LOCA curing steps can be repeated sequentially to obtain better water contact throughout the desired area.

In an exemplary embodiment, the light transmissive or substantially transparent, electrically conductive or thermally conductive path may be patterned onto the substrate or substrates prior to coating the substrate with a thermally cured LOCA. After lamination, current can be driven through its conductors to create localized heating, and thus partially cure the LOCA.

The chemically aged LOCA can also be selectively aged by patterning the crosslinking reagent onto a uniform coating of the monomer material. For example, the monomer can be coated by a slit, strip coated, microgravure, etc., and the crosslinker can then be assembled by non-contact patterning such as inkjet printing, spraying or stencil printing. Technology, to apply only to the desired position. In this way, LOCA may be selectively matured in certain regions with a high crosslink density, while other regions maintain little or no crosslinks to produce regions of high and low elastic modulus, and in some cases solid state and The area of liquid material.

Any of the above methods can be used to create a selectively patterned OCA layer. 2 illustrates an example embodiment of a structure that is assembled to allow for extreme bending of the display stack by using an area of softer OCA around the fold line 140. In some cases, the area of reduced toughness may be an air gap, an unmatured liquid, or an OCA having a lower modulus of elasticity. Figure 5 illustrates the allowable display Another exemplary embodiment of a selectively patterned OCA with stress relief at high strain when the stack 260 is folded. In the illustrated embodiment, the higher modulus of elasticity region 290 is surrounded by a lower modulus of elasticity region 280, which may be air, an unmatured liquid, or a lower modulus of elasticity OCA material. A fold line 270 can illustrate a line along which the display can be folded. The higher modulus region 290 may also be oriented at 90 degrees against the fold line to provide resistance to tight bending along the fold line.

Embodiments of the present invention can reduce stress transfer between adjacent layers of one of the substrate layers to allow for flexibility and flexibility of a stacked display. By varying the ratio of the modulus of elasticity between the materials and placing the material between the layers of the substrate, a central axis can be tuned to each layer depending on the desired flexibility and the position desired to bend. The overall toughness of a flexible display can be significantly reduced by bending the display stack more easily with lower force by strategically placing a low elastic modulus OCA between the layers. The low modulus OCA can be patterned to achieve a more desirable stress profile across one of the displays or a portion thereof.

In addition to regions that produce different elastic moduli, the above methods can be used to create regions having different indices of refraction that can be used to direct light depending on the geometry and orientation of the different regions. According to some embodiments of the present invention, selective aging of the OCA layer immediately adjacent to the display layer (e.g., immediately adjacent to the OLED display layer) can be used to selectively direct light that is allowed to exit from the display. A light guiding adhesive layer is introduced. For example, a light-guide adhesive layer can be used to follow the curvature of a three-dimensional glass window, or to increase the visible area of the display to obtain edge-to-edge view and bezel width reduction. Shrink.

A fiber optic plate can be produced by selectively crosslinking the cylindrical regions in the LOCA. Figure 6 illustrates a display stack 300 having a bottom substrate 340 and a top substrate 330 comprising a patterned OCA layer placement having a cylindrical region of higher refractive index 320 having a vertical alignment of about 1-50 microns in diameter. Between bottom substrate 340 and top substrate 330, the columnar regions are surrounded by an OCA 310 region (or air, uncooked liquid, etc.) having a lower index of refraction. This embodiment produces a composite OCA layer that behaves like a fiber optic panel and can optically direct images from the underlying display to the top surface of the display window.

According to certain example embodiments, a composite OCA layer comprising an aligned cylindrical OCA region having a relatively high refractive index 320 and a region having a relatively low refractive index 310 may be used to image from a display (eg, substrate 340). Guide to the edge of a larger cover. Figure 7 illustrates an exemplary embodiment in which a composite OCA layer can direct images from display substrate 340 to the edges of a larger cover glass substrate 350 to give side-to-side display content with minimal boundaries. An impression. In an extreme case, the composite OCA layer can be used to direct images from the display substrate 340 to the edge of a curved glass cover window 360 to give the impression of a edging display.

In an exemplary embodiment, a cylinder having a high index of refraction 320 may be formed by sequentially coating a water with a moisture-curable resin LOCA to a selected block and coating with LOCA. A tilted or curved cylinder may be formed by repeating the water coating and LOCA stratification steps while gradually changing the moisture pattern.

In an embodiment, a UV mask with a round aperture may be applied Under a first substrate, the first substrate is UV permeable. A source of UV radiation can be applied from under the substrate, while LOCA will only be inkjet printed at the location of the round holes. The ink jet printed LOCA can be substantially immediately matured to gradually form a cylinder. The position of the ink drop can be slightly displaced when the cylinder is formed because the UV radiation is directed through the cylinder as the cylinder is formed. The curved/curved cylinder array can be formed in this manner. As a final operational step, a fully overcoated LOCA layer may be applied and the top substrate laminated. The UV light may be directed along the cylinder again to form a mature bond to the uppermost substrate at the top of the cylinder.

Materials that may be used in flexible substrates in accordance with exemplary embodiments of the present invention may include polyethylene 2,6-naphthalene dicarboxylic acid (PEN), polyethylene terephthalate (PET), polyimine ( PI), polycarbonate (PC), polyethylene (PE), polyurethane (PU), polymethyl methacrylate (PMMA), polystyrene (PS), such as polyisoprene, polybutadiene, Natural rubber of polychloroprene, polyisobutylene, butyronitrile butadiene and styrene butadiene, saturated elastomer material such as polydimethyl siloxane (PDMS), oxime rubber, fluoroindene rubber, fluorine Rubber, perfluororubber, ethylene vinyl acetate (EVA) thermoplastic elastomer such as styrenic block copolymer, thermoplastic polyolefin, thermoplastic vulcanizate, thermoplastic polyurethane (TPU) thermoplastic copolyester, melt processable rubber. Metal foils may also be used in TFTs and special planarized metal foils on which the display can be produced.

The plurality of layers of a flexible display stack may also include, for example, an organic light emitting diode (OLED), a liquid crystal (LCD), a polymer dispersed liquid crystal (PDLC) or other reflective LCD display, electrophoresis (EP), and electric firefly. Light (EL), electrowetting (EW) electrochromic (EC) or such as based on suppressed internal reflection or Fabry-Beau A flexible display of other optical modulation effects of interference with the cavity.

In an exemplary embodiment where the flexible display is in a touch sensitive manner, the contact sensitive layer can operate based on resistive, optical, or capacitive contact sensing. The contact-aware layer may or may not be included as part of the display layer, in the form of intracellular or intracellular touch capabilities or using optically-aware pixels. Separate contact sensing layers based on resistive or capacitive touch may include conductive patterns established from materials such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide ( Transparent conductive metal oxide of AlZnO), poly(2,3-dihydrothiophene-1,4-dioxene)-poly(styrenesulfonic acid) (PEDOT:PSS), polypyrrole (Ppy), Silver nanowires, carbon nanotubes, and graphene-based materials including their graphene composites or any other suitable material.

Optical clear adhesives can be made from a variety of materials. Conventional LOCA can be made from acrylic, polyurethane, methyl methacrylate or silicone based materials. In addition to UV and thermal curing, certain oxime-based LOCA systems "moisture" can be cured (a combination of moisture and UV), and others can be chemically matured by the addition of a chemical crosslinker that may or may not Borrowed by a metal catalysis. Suitable examples include materials provided by Henkel Corporation such as their 319XX series of UV-cured acrylic and silicone resins, or 3M's 21xx series of UV-cured acrylic adhesives, Delo Corporation Photobond products and Dymax's UV-curable adhesive 9008.

Figure 8 is a flow diagram of a technique in accordance with an exemplary embodiment of the present invention. To understand the blocks of this flowchart, and the blocks in this flowchart Multiple combinations may be implemented by a variety of means. Accordingly, the blocks of the flowcharts are a combination of means of the means for performing the specified functions and combinations of operations for performing the specific functions. It is also to be understood that one or more of the blocks of the flowchart, and combinations of the blocks in the flowchart, may be implemented by a hardware-based computer system, or a combination of special-purpose hardware and computer instructions for performing a particular function. Implementation.

In this regard, the method illustrated in FIG. 8 in accordance with an embodiment of the present invention may include the step of depositing a layer of optically clear adhesive on a first substrate at step 410. Optically clear adhesives may be provided by any of the above means, including ink jet printing, screen printing, slit coating, strip coating, micro gravure printing, and the like. At step 420, a second substrate may be laminated to the optically clear adhesive. The optical clear adhesive may include a first region having a first modulus of elasticity and a second region having a second modulus of elasticity. The first modulus of elasticity may be higher (tougher) than the second modulus of elasticity.

In some embodiments, some or more of the operations may be modified or further expanded as described below. Again, in certain embodiments, additional optional operations may also be included. It will be appreciated that the following modifications, optional additional aspects, or expanded aspects may each be included with the above operations alone or in combination with any of the other features described herein. In certain embodiments, the optically clear adhesive of the first region may be crosslinked to a first degree, such as by being cured by exposure to UV radiation or heat. At step 430, the second region may be crosslinked to a different extent if necessary.

Numerous modifications and other embodiments of the inventions herein will be apparent to those skilled in the <RTIgt; Therefore, it is to be understood that the invention is not limited to the specific embodiments disclosed and modified The aspects and other embodiments are intended to be included within the scope of the appended claims. In addition, although the foregoing description and the associated drawings have described certain example embodiments in some example combinations of elements and/or functions, it should be understood that various combinations of elements and/or functions are not departing from the scope of the appended claims. The scope of the scope may be provided by alternative embodiments. In this regard, for example, a combination of elements and/or functions that are different from those explicitly described above are also to be understood as possibly referred to in certain subsequent claims. Although specific nouns are used herein, they are used in a broad and descriptive manner, and are not intended to be limiting.

134‧‧‧High elastic modulus area optical clear adhesive (OCA)

136‧‧‧Low elastic modulus area optical clear adhesive (OCA)

Claims (20)

A method of joining together a plurality of layers of a flexible display, comprising: depositing a layer of an optically clear adhesive on a first substrate; and laminating a second substrate onto the optically clear adhesive The first substrate is opposite to each other; wherein the first region of the optically clear adhesive comprises a first modulus of elasticity, wherein the optically clear adhesive comprises a second elasticity in a second region other than the first region The modulus, and the first modulus of elasticity thereof, is different from the second modulus of elasticity. The method of claim 1, wherein the optically clear adhesive comprises a liquid optical clear adhesive or a thin film optical clear adhesive. The method of claim 2, further comprising crosslinking the optically clear adhesive of the first region to a first degree, and crosslinking the optically clear adhesive of the second region to a second degree, the second degree Different from the first degree. The method of claim 3, wherein the crosslinking of the optically clear adhesive is carried out by exposure to ultraviolet radiation. The method of claim 4, wherein the second region of the optically clear adhesive is blocked from at least a portion of the ultraviolet radiation. The method of claim 3, wherein the crosslinking of the optically clear adhesive is carried out by applying heat. The method of claim 3, wherein the optically clear adhesive is associated It is carried out by application of a chemical crosslinking agent. The method of claim 1, wherein the layer of optically clear adhesive comprises a pattern of a first optically clear adhesive to form the first region of the optically clear adhesive. The method of claim 8, wherein the layer of optically clear adhesive further comprises a second pattern overlying a second optically clear adhesive to form the second region of the optically clear adhesive. The method of claim 8, further comprising wicking a second optical clear adhesive into the void formed between the first optical clear adhesive to form the second region of the optically clear adhesive. The method of claim 1, wherein the second modulus of elasticity is lower than the first modulus of elasticity, and wherein the second region of the optically clear adhesive defines a region of increased flexibility. An electronic device comprising: a display stack comprising: a first substrate; a layer of optically clear adhesive deposited on the first substrate; and a second substrate; wherein the optically clear adhesive The layer defines a first region having a first modulus of elasticity, wherein the layer of optically clear adhesive defines a second region having a second modulus of elasticity, and wherein the first modulus of elasticity is different And the second elastic modulus. The electronic device of claim 12, wherein the second modulus of elasticity is lower than the first modulus of elasticity, and the second region of the optically clear adhesive is defined to have a first region that is greater than the optically clear adhesive One of the regions of the display stack defined is a region of the display stack that is large in flexibility. The electronic device of claim 12, wherein the optically clear adhesive comprises a liquid optical clear adhesive. The electronic device of claim 14, wherein the liquid optical clear adhesive is crosslinked to a first extent in the first region and crosslinked to a second extent different from the first extent in the second region. The electronic device of claim 12, wherein the first region of the optically clear adhesive is cured in response to exposure to ultraviolet radiation. An electronic device comprising: a display stack comprising: a first substrate; a layer of optically clear adhesive deposited on the first substrate; and a second substrate; wherein the optically clear adhesive The layer defines a first patterned region having a first index of refraction, wherein the layer of optically clear adhesive defines a second patterned region having a second index of refraction, and wherein the first index of refraction Different from the second refractive index. The electronic device of claim 17, wherein the first patterned region and the The second patterned region comprises the same optically clear adhesive, and wherein the first patterned region is cured to a first extent, and wherein the second patterned region is cured to a second extent different from the first extent. The electronic device of claim 18, wherein the first patterned region is cured by exposure to ultraviolet radiation. The electronic device of claim 17, wherein the first patterned region and the second patterned region each comprise a different optically clear adhesive.